A wooden post shod with a metal tip rammed into the sea-bed as a datum-point. Note the nail at its top for securing a tape. The nail’s location 1m above the sea-bed level is tied into the datum level established on shore. (Colin Martin)

Donald MacKinnon of the Dumfries and Galloway Sub-Aqua Club (right) hands gravel-filled bags to Martin Dean of the Archaeological Diving Unit for emptying over exposed areas of the wreck during the winter of 1992. (Colin Martin)

Dr Robert Prescott of the Scottish Institute of Maritime Studies at the University of St Andrews lowering gravel-filled bags for emptying over exposed areas of the wreck during the winter of 1992. (Colin Martin)